A circular metal ring (radius r = 0.5 m) whose plane is perpendicular to a magnetic field B = 0.2 T carries 100 A. If the tension in the ring is 5N newtons (i.e., 5×N N), find N.
Physics · Mixed Chapter
JEE Mains

Question

A circular metal ring (radius r = 0.5 m) whose plane is perpendicular to a magnetic field B = 0.2 T carries 100 A. If the tension in the ring is 5N newtons (i.e., 5×N N), find N.

G1 Physics · Accepted Answer

Step 1 — Isolate half of the ring: Consider a semicircular half of the current-carrying ring. The field is perpendicular to its plane, so the net magnetic force on that semicircle equals I B times its chord length. Step 2 — Magnetic force: Chord length = 2r = 1 m. Fᵦ = I B(2r) = 100×0.2×1 = 20 N. Step 3 — Force balance: Two equal tensile forces T act at the two cut ends of the semicircle. Equilibrium requires 2T = Fᵦ = 20 N. Therefore T = 10 N. Step 4 — Given expression: T = 5N newtons ⇒ 5N = 1…